1. Technical Field
The present disclosure relates to a control system for controlling a light irradiation direction or a light irradiation range of a lamp installed in a vehicle such as an automobile. More particularly, the present disclosure relates to a light irradiation control system for a vehicle lamp, which can achieve a simpler configuration of a control unit or an actuator constituting the system.
2. Related Art
In the related art, various systems are known for controlling an optical axis direction of a lamp as one of the optical irradiation characteristics of a vehicle headlamp. Such systems include a leveling control system for constantly maintaining the irradiation angle with respect to the road surface by deflection-controlling the lamp optical axis in the upward and downward vertical directions in accordance with the changes in the pitch angle of the automobile or a swivel control system for irradiating a steering destination by deflection-controlling the lamp optical axis in the left and right horizontal directions in accordance with the changes in the steering angle of the automobile. For example, Japanese patent document JP-A-2000-118293 describes an apparatus for performing auto leveling control. This kind of auto leveling apparatus, as illustrated in FIG. 6, includes a vehicle height sensor Sh that detects changes in the front and rear vehicle height of the automobile in order to obtain the pitch angle of the automobile, a vehicle speed sensor Sv that detects the vehicle speed to determine whether to perform the leveling control in accordance with the vehicle speed change of the automobile, and a lighting switch sensor Ss that detects the lighting state of a headlamp at the leveling control timing. Also, in such an auto leveling apparatus, the respective detection outputs of these sensors are provided to a leveling ECU (Electronic Control Unit) 7X. The leveling ECU 7X performs predetermined calculations based on these detection outputs, and generates and provides a control signal for controlling the lamp optical axis of left and right headlamps RHL and LHL at a suitable leveling angle. Also, in these left and right headlamps RHL and LHL, leveling actuators (ACTs) 5R and 5L for vertically deflecting the lamp optical axis are installed to perform, respectively, leveling control of the lamp optical axis of the left and right headlamps RHL and LHL through drive control of the left and right leveling ACTs 5R and 5L by means of the control signal from the leveling ECU 7X.
In order to generate the leveling control signal, the leveling ECU 7X is provided with noise removal units 711 and 712 for removing noise included in the detection outputs from the respective sensors, a vehicle height calculation unit 713 that obtains a vehicle height value by performing a predetermined calculation based on the detection output of the vehicle height sensor, a vehicle height initialization unit 714 that corrects an assembly error when the vehicle height sensor Sh is assembled in an automobile, a vehicle speed calculation unit 715 that obtains a vehicle speed value by performing a predetermined calculation based on the detection output from the vehicle speed sensor Sv, and a lighting state determination unit 716 that determines the light state from the output of the lighting switch Ss. Further, the leveling ECU 7X is provided with a leveling angle calculation unit 717 that calculates the proper leveling angle based on the determination of the vehicle height value initialized by the vehicle height initialization unit 714, the vehicle speed value, and the lighting state, and provides a leveling angle as the leveling control signal.
If an automobile provided with the foregoing leveling control system also is provided with the swivel control system, the vehicle height sensor Sh, the vehicle speed sensor Sv, and the lighting switch sensor Ss can be used commonly in the respective systems, but a swivel ECU for generating a swivel control signal needs to be provided independently of the leveling ECU. As illustrated in FIG. 6, in order to generate the swivel control signal based on the detection outputs from the vehicle speed sensor Sv, a steering angle sensor Sθ and the lighting switch sensor Ss, the swivel ECU 8X is provided with noise removal units 811 and 812 for performing a noise removal process on respective outputs of the vehicle speed sensor Sv and the steering angle sensor Sθ. The ECU 8X also is provided with a vehicle speed calculation unit 813, a steering angle calculation unit 814, and a lighting state determination unit 815 which perform, respectively, the vehicle speed calculation, steering angle calculation, and lighting state determination in accordance with the outputs of the vehicle speed sensor Sv, the steering angle sensor Sθ, and the lighting switch sensor Ss. The swivel ECU 8X is also provided with a swivel angle calculation unit 816 to calculate the swivel angle based on the outputs. The swivel ECU 8X may perform the same process as the leveling ECU 7X. Thus, in this case, the noise removal units 711 and 811, the vehicle speed calculation units 715 and 813, and the lighting state determination units 716 and 815 are equivalent to each other, respectively. Since the leveling ECU and the swivel ECU are provided with the same units as described above, the corresponding constituent units are present in duplicate when the leveling ECU and the swivel ECU are combined together, especially in automobiles provided with both the leveling control system and the swivel control system. This situation can lead to an increase in the system size and cost. Also, when the respective ECUs operate simultaneously, the respective constituent units perform the same calculation of the operation values or the same state determination, and thus unnecessary power consumption occurs.